Guides
Practical walkthroughs behind the tools — how the formats and the math actually work. Every guide links to the tool that does the job.
Latest
Reduce EMI or reduce tenure after a part payment: which saves more?
Both lower your total interest, but not by the same amount. Here's the trade-off, a worked example, and how to compare your own loan.
August 31, 2026
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August 31, 2026
How to calculate a home loan foreclosure amount
Outstanding principal, accrued interest, charges and tax — what goes into a loan foreclosure (pre-closure) figure, and why the bank's number can differ.
August 31, 2026
How to read JSON with a tree viewer
A tree viewer turns a wall of brackets into a structure you can expand, search and copy paths from. Here's how to use one effectively.
August 31, 2026
JSON parse errors explained: 'Unexpected token', 'Expected comma or brace', and the rest
What each common JSON error message actually means, the usual cause, and how to find the spot fast using line and column.
August 29, 2026
How to convert images to PDF (JPG, PNG, phone photos)
Turn one or several JPG or PNG images into a single PDF, in the right page order — what the tool does, the steps, and the common snags.
August 29, 2026
How to merge PDF files into one
Combine two or more PDFs into a single file, in the order you choose — the steps, what merging does to quality and size, and how to handle pages and images.
August 29, 2026
How to compress a PDF to under 1 MB
A 1 MB upload limit is common on application portals. Here's what's realistic, how to get there, and when 1 MB simply isn't possible without losing the text.
August 29, 2026
How to compress a PDF for email attachments
Gmail, Outlook and most providers cap attachments around 20–25 MB. Here's how to get a PDF under the limit — or send it without shrinking it at all.
August 29, 2026
How to compress a PDF to 100 KB
100 KB is a hard target that only works for some PDFs. Here's when it's realistic, how to get there, and what you lose along the way.
August 29, 2026
How to reduce PDF size without losing quality
"Without losing quality" means different things for scans and for text PDFs. Here's what's actually possible and how to get the smallest safe result.
August 29, 2026
Why is my PDF so big? (and what to do about it)
PDFs balloon for a small number of reasons — scanned pages, embedded photos, fonts. Here's how to tell which one is yours and fix it.
August 29, 2026
How to convert a PDF to JPG
Turn PDF pages into JPG images — one page or all of them — and how to choose between JPG and PNG for the result.
August 29, 2026
How to convert a PDF to PNG
Export PDF pages as lossless PNG images — best for text, diagrams and screenshots — and when to use JPG instead.
August 29, 2026
How to split a PDF into separate files
Split a PDF by page range, pull out a section, or break it into one file per page — the steps and the common cases.
August 29, 2026
How to make a PDF from any file
The quickest route from images, documents or web pages to a PDF — and which conversions genuinely need desktop software.
August 29, 2026
PDF and photo size limits for online application forms
Government, bank and exam portals cap uploads at 1 MB, 500 KB or less. Here's how to read the requirement and hit it without ruining the document.
August 29, 2026
How to combine scanned pages into one PDF
You scanned a document and ended up with separate image or PDF files per page. Here's how to merge them into a single, correctly-ordered PDF.
August 29, 2026
How to convert JPG to PDF on your phone
Turn photos into a PDF straight from an Android phone or iPhone — in the browser, with no app to install.
August 29, 2026
How to combine a PDF and images into one file
You have a PDF plus a few JPGs or PNGs and need them as a single document. Here's the two-step way to do it in the browser.
August 29, 2026
How to resize a photo and signature for online forms
Application portals want the photo and signature at exact pixel sizes and tiny file sizes. Here's how to hit both without an app.
August 29, 2026
iLovePDF free limits — and how Useful Hacks compares
What the iLovePDF free tier actually restricts, and where a no-signup browser-based toolkit does the same job without the caps.
August 29, 2026
Smallpdf free limits explained
The Smallpdf free tier's task-per-hour cap and watermark, what triggers them, and a no-limit browser alternative for the basics.
August 29, 2026
The best free PDF tools with no signup
What "free, no signup" actually means across the popular PDF sites, and how to pick one for a quick one-off task.
August 29, 2026
How to compress images for the web without them looking bad
Why images make pages slow, how much quality you can drop before anyone notices, and a repeatable way to hit a size target.
August 29, 2026
How to resize an image without losing quality
What 'without losing quality' really means when you resize, why enlarging is different from shrinking, and how to keep proportions intact.
August 29, 2026
JPG, PNG or WebP: which image format should you use?
A practical guide to picking an image format — what each one is good and bad at, and when to convert.
August 29, 2026
How to edit a photo in your browser (no app, nothing uploaded)
Rotate, straighten, adjust and filter a photo without installing anything — and without the file leaving your device.
January 25, 2026
SIP vs. lumpsum: what the math actually says
Systematic investing and lump-sum investing solve different problems. Here's how to reason about which one fits your situation.
January 20, 2026
How to compress a PDF without wrecking it
What actually makes PDFs large, why some compressors do more damage than others, and how to pick the right approach for your file.
January 15, 2026
How to calculate EMI (and why the formula looks so intimidating)
A plain-English walkthrough of the EMI formula, what each variable means, and a worked example you can check by hand.
January 10, 2026
How to format JSON (and actually understand the errors)
JSON looks like a JavaScript object but follows stricter rules. Here's what those rules are and how to read the errors when they're broken.